The present invention relates in general to an improved generator junction assembly, and more particularly, to an improved generator parallel ring to main lead junction assembly for use in a turbine generator within a power generation plant.
Many power generation plants produce electricity by converting energy (e.g. fossil fuel, nuclear fission, hydraulic head, geothermal heat) into mechanical energy (e.g. rotation of a turbine shaft), and then converting the mechanical energy into electrical energy (e.g. by the principles of electromagnetic induction). Fossil fuel power generation plants typically use a turbine to convert the fossil fuels into mechanical energy and a generator to convert the mechanical energy into electricity.
One aspect of the above-described power generation scheme involves a junction assembly that is located between the generator""s parallel rings and the generator""s main lead. The junction assembly conducts AC electrical current from the parallel rings to the main lead. The junction assembly must also accept and attenuate the vibration that the parallel rings and coil windings place upon it, as well as withstand the temperatures caused by the electrical current that runs through it.
As shown in FIG. 1, to meet these requirements, a conventional junction assembly 10 typically comprises several flexible connectors 12 (sometimes set back-to-back) secured to a thin, flat elongated junction 14. The flexible connectors 12 are constructed of conductive wire strands 16 to provide an electrically conductive path and to provide the junction assembly 10 with flexibility to accept the various and varying forces and loads applied by the parallel rings 20, main lead 22 and other generator components. The junction 14 secures the flexible connectors 12 relative to the parallel rings 20 and main lead 22, and has a passageway 18 through which a coolant flows to cool the flexible connectors 12 by conduction.
There are several shortcomings, however, to the above-described conventional junction assembly. One shortcoming involves the relatively elongated configuration of the junction assembly. Since electrical current desires to flow toward the perimeter of the junction assembly through a phenomenon known as alternating current (AC) current crowding (where current desires to flow along the ends or perimeter of an object), this elongated configuration undesirably draws current away from the centrally positioned flexible connectors and toward the perimeter of the junction assembly. Also, the junction assembly typically experiences about 20 mils of vibrational force during each of several million cycles, which is greatest toward the perimeter of the junction assembly. Thus, elongated configurations do a poor job in attenuating this vibrational force. Another shortcoming involves the difficulty in attaching and detaching the flexible connectors to the junction and otherwise assembling and disassembling the junction assembly. Another shortcoming involves the need to custom design the junction assembly configuration to accommodate the particular configuration and requirements of the generator with which it is used.
There is thus a need for a junction assembly that inhibits current crowding from the flexible connectors. There is also a need for a junction assembly with improved vibration attenuation. There is also a need for a junction assembly having flexible connectors that can be relatively easily attached and detached to the junction. There is also a need for a junction assembly having a configuration that can be readily modified to accommodate the particular configuration and requirements of the generator with which it is used, such as with different cooling gas and water configurations.
One aspect of the present invention thus involves a junction assembly, comprising a first electrically conductive junction having at least one channel and at least one coolant inlet and a second electrically conductive junction having at least one channel and at least one coolant outlet; and at least one electrically conductive flexible connector having a first end and a second end, at least a portion of the first end sized and configured to fit within at least a portion of the channel of the first junction and at least a portion of the second end sized and configured to fit within at least a portion of the channel of the second junction. Each of the at least one flexible connector can be secured to the first junction by passing a bolt through a first bolthole in the flexible connector and a bolthole in the first junction, and each of the at least one flexible connector can be secured to the second junction by passing a bolt through a second bolthole in the flexible connector and a bolthole in the second junction.
Another aspect of the present invention involves a junction for use in a generator adapted to connect a main lead with parallel rings, comprising a plurality of channels, each channel having a depth between about 1 inch and about 10 inches and a width between about 0.5 inch and about 2 inches; and at least one coolant avenue that comes within at least about 1 inch of each channel; and at least one bolt hole that intersects the plurality of channels.
Another aspect of the present invention involves a method of securing a plurality of flexible connectors to a junction of a junction assembly used in generator, comprising inserting a least a portion of at least one conductive flexible connector into at least one channel of a conductive junction; aligning a bolt hole in the flexible connector with a bolt hole in the junction; and passing a bolt through the aligned bolt holes and; securing the bolt with a nut.
Further aspects, features and advantages of the present invention will become apparent from the drawings and detailed description of the preferred embodiment that follows.